This invention relates to optical test instruments, and more particularly to array connector test harnesses for single-ended optical test instruments.
Array connectors, such as MPO/MTP® connectors (MPO is an industry acronym for multi-fiber push on connectors, MTP® is a brand of MPO connector), contain multiple fibers aligned in an array. Most common is 1×12 but 2×12 and other configurations are available. However, test instruments are designed to interface to single fiber connectors. These single fiber connectors are sometimes aggregated into a duplex link and some test instruments are designed to interface to these. No test instruments are configured to interface to array connectors.
To accommodate this lack of interface to array connectors, prior art requires a custom harness that breaks-out the array connector interface to simplex connectors, see FIG. 1. The tester may then be connected to the first simplex connector and the first fiber tested. The tester then must be disconnected and subsequently connected to the next and subsequent connectors to test the next and subsequent fibers in the array. Ideally, the length of fiber in the break-out harness is long enough to suppress the effects of the tester's deadzone (the length during which reflections return too quickly after the stimulus to be detected by the tester).
The harness comprises launch-cord end and tail-cord end harnesses 12, 14, which connect to respective array connectors 16, 16′, the array connectors interfacing with the fiber network under test 18. It is noted that the fiber network comprises plural fibers with ones of the fibers corresponding to ones of the connections of the array connector. The near-end harness 12 comprises plural launch cord connection fibers 20, 20′, 20″, etc., with interface connectors 22, 22′, etc. adapted for connection to a test instrument 24. Tail-cord breakout harness 14 has a corresponding set of breakout fibers 26, 26′, etc. with connectors 28, 28′, etc. for connection to a test instrument.
FIG. 2 illustrates the testing steps involved with testing in accordance with the prior art. To accomplish a testing of a fiber link, at step 1, a first fiber of the set of fibers is selected and the launch-cord breakout connector 20 (for example) of that fiber is connected to the test instrument, the tail-cord breakout connector 26 is connected at the far end of the fiber, and a testing sequence is performed. Next, the test instrument is connected to a different launch-cord breakout fiber 20′ with the tail-cord breakout connector 26′ connected to the far end of the fiber (step 2), and a testing sequence is performed. Subsequent launch-cord breakout fibers 20″, 20′″, 26″, 26′″, etc. are connected and testing performed, until the full set of fibers (or a desired subset) has been tested.
Next, the test instrument is moved to the far end of the fiber network, the tail-cord and launch-cord breakout fiber connectors are moved to the opposite end of the fiber, with tail-cord breakout fiber 26 connected to the remote end and launch-cord breakout fiber 20 connected at the near end (which formerly was the remote end), whereupon a test sequence is initiated, step 3. Once that testing is complete, the test instrument is connected to a different launch-cord breakout fiber 20′ and tail-cord breakout fiber 26′ (step 4) and a testing sequence is performed. Subsequent tail-cord/launch-cord breakout fibers 20″/26″, 20′″/26′″, etc. are connected and testing performed, until again the full set of fibers (or a desired subset) has been tested.
The above steps effect full bi-directional testing of the fiber network, but require careful monitoring of the testing sequences and steps to ensure that all the fibers are appropriately tested. Also, the testing steps, including requiring moving the test instrument to opposite ends of the network, can be time consuming.